Method of chemical embossing

ABSTRACT

AN IMPROVE PROCESS FOR THE CHEMICAL EMBOSSING OF A THERMOPLASTIC SHEET COMPRISING BLENDING (1) A VINYL RESIN, E.G., POLYVINYLCHLORIDE, (2) A PLASTICIZER FOR THE VINYL RESIN, (3) A BLOWING AGENT WHICH DECOMPOSES WHEN HEATED AT A TEMPERATURE IN THE RANGE ABOVE THE GLASS TRANSITION TEMPERATURE OF THE PLASTICIZED VINYL RESIN AND BELOW THE DECOMPOSITION TEMPERATURE OF THE RESIN, (4) A LINEAR POLYESTER CONTAINING AT LEAST TWO OLEFINICALLY UNSATURATED SITES AND CAPABLE OF FURTHER POLYMERIZATION OF COPOLYMERIZATION IN THE PRESENCE OF AN ADDITION POLYMERIZATION CATALYST; AND (5) A MONOMER CONTAINING ONE OLEFINICALLY UNSATURATED SITE AND CAPABLE OF COPOLYMERIZATION WITH THE POLYMER OF (4) IN THE PRESENCE OF AN ADDITION POLYMERIZATION CATALYST. SUCH A BLENDED COMPOSITION IS FORMED INTO A SHEET AND TO SUCH SHEET IS APPLIED, IN A PRE-DETERMINED PATTERN, A COMPOSITION COMPRISING (A) A CATALYST THAT WILL CAUSE POLYMERIZATION OF THE SYSTEM AND, OPTIONALLY, (B) A LIQUID THAT WILL PENETRATE THE SHEET, THE FOAMING OF THE SHEET AND CREATION OF THE EMBOSSED EFFECT IS ACCOMPLISHED BY HEATING THE RESULTING SHEET TO A TEMPERATURE SUFFICIENT TO FUSE THE PLASTICIZED RESIN, DECOMPOSE THE BLOWING AGENT, AND POLYMERIZE THE OLEFINICALLY UNSATURATED COMPONENT OR COMPONENTS.

United States Patent 3,823,214 METHOD OF CHEMICAL EMBOSSING John L. H.Allan, Easton, and Nathan D. Field, Allentown, Pa., assignors to GAFCorporation, New York,

No Drawing. Continuation-impart of abandoned application Ser. No.867,404, Oct. 17, 1969. This application Feb. 22, 1972, Ser. No. 228,303

Int. Cl. B32b 3/26, 27/30 US. Cl. 26452 10 Claims ABSTRACT OF THEDISCLOSURE An improved process for the chemical embossing of athermoplastic sheet comprising blending (1) a vinyl resin, e.g.,polyvinylchloride,

(2) a plasticizer for the vinyl resin,

(3) a blowing agent which decomposes when heated at a temperature in therange above the glass transition temperature of the plasticized vinylresin and below the decomposition temperature of the resin,

(4) a linear polyester containing at least two olefinically unsaturatedsites and capable of further polymerization of copolymerization in thepresence of an addition polymerization catalyst; and

(5) a monomer containing one olefincally unsaturated site and capable ofcopolymerization with the polymer of (4) in the presence of an additionpolymerization catalyst.

Such a blended composition is formed into a sheet and to such sheet isapplied, in a predetermined pattern, a composition comprising (a) acatalyst that will cause polymerization of the sys tem and, optionally,(b) a liquid that will penetrate the sheet.

The foaming of the sheet and creation of the embossed effect isaccomplished by heating the resulting sheet to a temperature sufiicientto fuse the plasticized resin, decompose the blowing agent, andpolymerize the olefinically unsaturated component or components.

This application is a continuation-in-part of our co pending applicationSer. No. 867,404 filed Oct. 17, 1969 and now abandoned.

The present invention is directed to a process of producing an embossedeffect on a foam decorative material, e.g., a decorative surfacecovering; more particularly, the present invention is directed to aprocess of producing such embossed effect chemically without the use ofmechanical embossing.

The mechanical embossing of foamed or cellular sheets, in combinationwith printing, has always presented several problems. It has beendiflicult to achieve sharp edges and sharp lines of demarcation in theembossed areas when dealing with foamed structures. Where printing iscarried out in addition to the embossing, the problem of attainingregister between the embossing rolls and the printing rolls has beenexceedingly difiicult. The difficulty increases with the width of theembossed and printed sheet. Therefore, there has been a need for animproved method of imparting an embossed appearance to the thermoplasticsheet.

To eliminate these deficiencies and disadvantages of conventionalmechanical embossing of foamed or cellular sheets in combination withprinting, various methods of chemical embossing have been developed. Allof these methods generally involve the selective retardation orpromotion of the foaming of a plastisol or organosol composition so thatthe resultant product will have both unfoamed and foamed regions.

Thus, while it has been previously proposed to blend with a vinyl resinthermoplastic sheet one or more monom'eric materials having a single ormultiplicity of unsaturated sites so as to produce a cross-linkingeffect with the vinyl polymer to thereby provide areas unetfected bysubsequent foaming, thereby producing a chemical embossed eifect, it hasnow been found in accordance with the present invention that such achemical embossed effect can be provided by including within athermoplastic sheet comprising a vinyl resin, plasticizer, and blowingagent, a polymer containing at least two olefinically unsaturated sites,and capable of polymerization or copolymerization in the presence of anaddition polymerization catalyst, and, a monomer containing oneolefinically unsaturated site and capable of copolymerization with suchpolymer. In this way, it has been found possible to effect theproduction of a chemical embossed pattern on a foamed decorative surfacein a manner not heretofore possible by prior art processes. In thisconnection, it has been discovered in accordance with the presentinvention that the use of a polymer containing at least two olefinicallyunsaturated sites has substantial economic advantages over any and allpreviously proposed chemical embossing processes.

Accordingly, it is a principal object of the process of the presentinvention to provide for the production of chemically embossed foameddecorative sheets, particularly foamed decorative surface coverings, ina manner not contemplated by the prior art and eliminating the inherentdisadvantages thereof.

It is a further object of the present invention to provide a process forthe chemical embossing of thermoplastic sheets, by which a foameddecorative effect is produced through the employment of a polymercontaining at least two olefinically unsaturated sites such polymerbeing capable of further polymerization or copolymerization in thepresence of an addition polymerization catalyst.

It is still a further object of the present invention to provide such aprocess for the chemical embossing of thermoplastic sheets by which afoamed decorative effect is produced through the conjoint employment ofsuch a polymer containing at least two olefinically unsaturated sitesand a monomer containing one olefinically unsaturated site and capableof copolymerization with such polymer.

Still further objects and advantages of the novel process of the presentinvention will become more apparent from the following more detaileddescription thereof.

The above objects and advantages of the process of the present inventionare achieved through an improvement associated with the chemicalembossing of foamed decorative sheet materials and foamed decorativesurface covering materials in particular. Thus, it has been found inaccordance with the present invention that a great economic andindustrial improvement can be achieved by conducting a process for thechemical embossing 0f foamed decorative sheet materials through theempolyment of a polymeric material having at least two olefinicallyunsaturated sites capable of further polymerization or copolymerizationin the presence of an addition polymerization catalyst. Thus, theprocess of the present invention comprises an improvement in thechemical embossing of thermoplastic sheet material, particularly, sheetmaterial comprising polymers and copolymers of vinyl chloride. Thus, theprocess of the present invention comprises an improvement in a processof imparting an embossed appearance to a thermoplastic sheet of a vinylchloride resin containing a plasticizer for the vinyl resin and a blowinagent which decomposes when heated at a temperature in the range abovethe glass transition temperature of the plasticized vinyl resin andbelow the decomposition temperature of the resin. Further, the processof the present invention is conducted through the conjoint use of such apolymer containing at least two olefinically unsaturated sites and amonomer containing one olefinically unsaturated site and capable ofcopolymerization with such polymer in the presence of an additionpolymerization catalyst. Again, such materials are incorporated in avinyl sheet, e.g., polyvinylchloride, containing a plasticizer for thevinyl resin and a blowing agent which decomposes when heated at atemperature in the range above the glass transition temperature of theplasticized vinyl resin and below the decomposition temperature thereof.A mixture as defined above is formed into a sheet upon which is laterapplied a liquid that will penetrate the sheet and cause thepolymerization of the system through the catalyst effect. Finally, theresulting sheet is heated to a temperature within the range of, forexample, 300 to 450 F. to fuse the plasticized resin, decompose theb1owing agent, and further polymerize or copolymerize the polymericsystem.

Generally, the process of the present invention directed to theproduction of embossed appearance on a thermoplastic sheet comprisesblending (1) a vinyl resin,

(2) a plasticizer for the vinyl resin,

(3) a blowing agent which decomposes when heated at a temperature in therange above the glass transition temperature of the plasticized vinylresin and below the decomposition temperature of the resin,

(4) a polymer containing at least two olefinically unsaturated sites andcapable of further polymerizing or copolymerizing at elevatedtemperatures in the presence of an addition polymerization catalyst, and

(5) a monomer containing one olefinically unsaturated site and capableof copolymerization with said polymer at elevated temperatures in thepresence of an addition catalyst.

Such a composition or blend is formed into a sheet and applied to suchsheet, in a pre-determined pattern, is a composition comprising (a) acatalyst that will cause polymerization of the system, i.e., theolefinically unsaturated polymer and monoolefinically unsaturatedmonomer, and optionally,

(b) a liquid that will penetrate the sheet.

Subsequently, the sheet to which has been applied in a pre-determinedpattern the above composition is heated to a temperature sufficient tofuse the plasticized resin, decompose the blowing agent, and furtherpolymerize or copolymerize the system. By such a process, the portion ofthe sheet to which has been applied the composition containing thecatalysts and optionally penetrating liquid will remain substantiallyunfoamed due to the restricting character of the polymerization orcopolymerization product, while the portion to which the catalyst hasnot been applied will be fully foamed. This, of course, will result inproducing a patterned, embossed effect containing high areas, fullyfoamed areas, and valleys, i.e., areas in which foaming has beenchemically restricted.

Alternatively, in accordance with the process of the present invention,the catalysts and optional penetrating liquid may be applied to asupporting sheet with the vinyl resin blend being applied to thesupporting sheet above the catalyst. Heating such a material tosufiicient temperature to fuse the blend, decompose the blowing agent,and further polymerize or copolymerize the system will effect the samechemical embossing appearance of the vinyl sheet product having bothcompletely foamed and unfoamed areas.

In accordance with the present invention, any thermoplastic resin can beemployed which is capable of being formed into films or sheets. Suchresins preferably comprise vinyl resins; and more preferably, polymersand copolymers of vinyl chloride. Thus, while polyvinylchloride itselfis the preferred vinyl resin employed in accordance with the process ofthe present invention, copolymers of vinyl chloride with comonomers, forexample vinyl esters such as vinyl acetate, vinylidene chloride, vinylpropionate, and vinyl butyrate, lower alkyl vinyl ethers such as methyl,ethyl, propyl, isopropyl, butyl and isobutyl vinyl thereof such asmethyl to butyl acrylates and methacrylether, and acrylic acid compoundssuch as acrylic acid, methacrylic acid, and the lower (C alkyl estersates, or a mixture of polyvinylchloride with at least one polymerderived from such comonomers may also be employed.

When unusually excellent properties of abrasion resistance, toughness,and tensile strength are not required, as may well be the case with awall covering or other merely decorative application, other materialsmay be used as a thermoplastic resin. Examples of such materials includepolystyrene, haloand lower alkyl-substituted polystyrenes, polyolefinssuch as polyethylene and polypropyl ene, and acrylic acid compounds suchas acrylic acid,

methacrylic acid and their C lower alkyl esters and the like. Thethermoplastic resins are those formed by addition polymerization asopposed to the normally nonthermoplastic resins usually formed bycondensation. The glass transition temperature of these resins is thetemperature at which the resin changes from a hard, brittle solid to aflexible solid. Increasing plasticization of the resin increasinglylowers the glass transition temperature. As a practical matter, theglass transition temperature of the resin lies close to the gellationtemperature of the resin dispersed in a plasticizer even though theinitial gellation temperature is rate sensitive.

In producing the thermoplastic resin blend utilized in accordance withthe process of the present invention, the thermoplastic resin asdescribed above will be combined with one or more conventionalplasticizers. Esters of straight and branched chain alcohols withaliphatic acids impart low viscosity and good viscosity stability.Typical plasticizers of this type include dibutyl sebacate, dioctylse'bacate, dioctyl adipate, didecyl adipate, dioctyl azelate,triethylene glycol di(2-ethylhexanoate), diethylene glycoldipelargonate, triethylene glycol dicaprylate,2,2,4-trimethyl-1,3-pentanediol diisobutyrate, and the like.Plasticizers of the aromatic type, such as esters of aliphatic alcoholsand aromatic acids or aromatic alcohols and aliphatic acids or aromaticalcohols and aromtic acids are desirable in that they impart goodfoaming characteristics to a plastisol, although the use of highlyaromatic plasticizers is limited by their tendency to yield plastisolsof high viscosity. Typical plasticizers of this type include dibutylphthalate, dicapryl phthalate, dioctyl phthalate, dibutoxy ethylphthalate, dipropylene glycol dibenzoate, butyl benzyl sebacate, butylbenzyl phthalate, dibenzyl sebacate, dibenzyl phthalate and the like.Other types of plasticizers, such as esters of inorganic acids,including tricresyl phosphate, octyl diphenyl phosphate and the like,alkyd derivatives of rosin, chlorinated paraffine, high molecular weighthydrocarbon condensates and the like can also be used. The plasticizeror blend of plasticizers is chosen to yield a composition of the desiredviscosity and/or foaming characteristics. In addition, the plasticizershould preferably have a low vapor pressure at the temperatures requiredto fuse the resin. A vapor pressure of two millimeters of mercury orless at 400 F. has been found particularly satisfactory.

Generally, the plasticizer is blended with the thermo plastic resin in arange of from 20 to 130 parts by weight of the plasticizer per parts byweight of the resin. Of course, greater or lesser amounts of theplasticizer can be employed, the amount of plasticizer generally beingdetermined by the selection of the particular plasticizer, theparticular resin, and the utility of the final product.

Minor amounts of stabilizer are usually incorporated in the coatingcompositions to reduce the effects of degradiation by light and heat.Suitable light stabilizers include phenyl phthalate, phenyl benzoate,o-tolyl benzoate, o-nitrophenol, and organic phosphates and othercomplexes of such metals as barium, cadmium, calcium, zinc, strontium,lead, tin and the like. Suitable heat stabilizers include sulfides andsulfites of aluminum, silver, calcium, cadmium, magnesium, cerium,sodium, strontium, and the like, leucine, alanine, oand p-amino benzoicacid and weak acid radicals including ricinoleates and abietates, andthe like.

Normally, the compositions contain about 0.5 to about 5 parts stabilizerper 100 parts resin. The stabilizer in foamable compositions can exertinfluence on the decomposition of the blowing agent. Some stabilizersserve as catalyst causing the decomposition to take place at a lowertemperature.

In accordance with the process of the present invention, a blowing agentis incorporated in the blend of the vinyl resin. The blowing agent,comprising another essential component of the resin blend, is one whichdecomposes to liberate and inert gas such as nitrogen, carbon dioxide orthe like when heated at a temperature within the range of above theglass transition temperature of the plasticized vinyl resin and belowthe decomposition temperature of the resin. Such blowing agent employedin accordance with the process of the present invention should beuniformly distributed throughout the resin-plasticizer blend. A numberof blowing agents particularly applicable for the blowing or foaming ofvinyl resins and polyvinylchloride in particular are commerciallyavailable, the most widely used of these being azobis formamide. Suchmaterial normally decomposes at a temperture of about 390 F. in air.Because of this relatively high decomposition temperature, such ablowing agent is particularly adapted for use in the process of thepresent invention and, thus, is preferred. Other conventional blowingagents, however, can be suitably employed in accordance with theimproved process of the present invention. Such conventional blowingagents include, for example:

Azobisisobutyronitrile N,-N'-dimethyl-N,N'-dinitrosoterephthalamidep,p'-Oxybis (benzenesulfonylhydrazide) p,p'-Oxbis(benzenesulfonylsemicarbazide) Barium azodicarboxylateDinitrosopentamethylenetetramine, etc.

Thus, as noted from the above, the conventional blowing agents useful inthe blowing or foaming of vinyl resins and polyvinylchloride inparticular generally fall within the general class of substitutedhydrazides, substituted azo compounds, and substituted nitrosocompounds. In this regard, any of the conventionally employed blowingagents useful in the foaming of vinyl resins can be employed inaccordance with the process of the present invention, the above notedparticular foaming agents only being representative of those which areuseful. Thus, it is only necessary that the blowing agent employed inaccordance with the process of the present invention be one whichdecomposes when heated at a temperature in the range of above the glasstransition temperature of the plasticized vinyl resin and below thedecomposition temperature of the vinyl resin.

As a general rule, the preferred minimum decomposition temperature ofthe blowing agent should be about 300 F., the decomposition temperatureof polyvinylchloride being, for example, about 400 F. Accordingly, theblowing agent should be one which decomposes within such temperaturerange, or, more practically, within the temperature range of 300 F. to450 F, the temperature at which a stabilized vinyl resin compositionwill normally decompose.

While the aomunt of blowing agent employed in accordance with theprocess of the present invention is not critical and the same need onlybe employed in an amount so that effective foaming can be achieved whenthe blowing agent is thoroughly distributed throughout theresinplasticized mixture, the blowing agent will normally be present inan amount within the range of 0.5% to 15%.

It is common practice to add accelerators or catalysts to thecompositions to accelerate the decomposition of the blowing agents,reduce the decomposition temperature and/or narrow the decompositiontemperature range. Typical types of accelerators are various metal saltssuch as dibasic lead phosphite, dibasic lead stearate, dibasic leadphthalate and similar lead salts, zinc salts such as zinc laurate, zincoxide, zinc stearate, zinc carbonate, zinc salt ofmercaptobenzothiazole, zinc octoate, zinc naphtholate, zinc dust, andcadmium octoate. These agents can also serve as stabilizers for thecomposition. Accelerators can be very effective for broadening thedecomposition temperature differential between the inhibited blowingagent and the remaining blowing agent. In this specification and claims,the designation blowing agent is intended to include not only blowingagent itself, but also the combination of a blowing agent with anaccelerator.

As indicated previously, in accordance with the improved process of thepresent invention, the vinyl resinplasticizer blend has incorporatedtherewith a polymerizable system comprising a polymer having at leasttwo olefinically unsaturated sites and a monomer containing a singleolefinically unsaturated site. Such a system not only polymerizes underthe conditions to be described hereinafter, but also tends to causecross-linkages of the polyvinyl resin chains. It is this polymerizationand crosslinking effect which apparently effectively prevents, retards,inhibits, or minimizes the foaming of the vinyl resin sheet in thoseareas in which the sheet has been coated with the polymerizationcatalyst. Aside from the unsaturated characteristics of thepolymerizable components employed in accordance with the improvedprocess of the present invention, they must be compatible with theplasticized vinyl resin (miscible therewith and capable of beingintimately dispersed within the vinyl resin system) and must bepolymerizable in the presence of an addition polymerization catalyst ata temperature above the glass transition temperature and below thedecomposition temperature of the plasticized vinyl resin system.

As indicated above, one of the essential components incorporated in thethermoplastic sheet in accordance with the process of the presentinvention comprises a polymer containing at least two olefinicallyunsaturated sites and capable of further polymerization orcopolymerization in the presence of an addition polymerization catalyst.In this regard, it is quite unexpected that such polymeric materialswhich contain a plurality of relatively unreactive ethylenicallyunsaturated groups would be sufiiciently effective as copolymerizableagents and cross-linking agents to restrain the expansion of a foamablecomposition at elevated temperatures in the chemical embossing processof the present invention. Additionally, the polyolefinically unsaturatedpolymeric material which is employed should be one which is compatiblewith the vinyl resin, e.g. polyvinylchloride, and one which is capableof copolymerizing therewith in order to produce a cross-link producthaving the necessary foam-restraining characteristic.

While a wide variety of polymers having at least two olefinicallyunsaturated sites are known, those employed herein comprise a group ofknown materials which may be described as poly-unsaturated linearpolyesters. Such polyesters may be produced by an esterificationreaction between a dibasic acid (or anhydride) and a glycol, one or bothof which are unsaturated, i.e. contain an olefinic or ethylenic linkage(double bond between adjacent carbon atoms).

Examples of saturated glycols (or mixtures thereof) which may be reactedwith an unsaturated dicarboxylic acid include ethylene glycol, 1,2- and1,3-propylene glycol, 1,2-, 2,3- and 1,4-butylene glycol, 1,5-, 2,3-,2,4- and 7 1,4-pentane-diol, 1,6-, 1,5-, 1,4-, 1,3-, 1,2-, 2,5-, 2,3-,2,4-, and 3,4-hexandiol, diethylene glycol, triethylene glycol,dipropylene glycol, isopropylidene bis-(p-phenyleneoxypropanol-Z), etc.

Examples of unsaturated glycols (or mixtures thereof) which may bereacted with either an unsaturated or saturated dicarboxylic acidinclude any of the glycols mentioned in the preceding paragraphcontaining an ethylenic linkage such as 2-butene-l,4-diol, 2- and3-pentene-l,5- diol, 2-, 3- and 4-hexene-l,4-, -l,5- and -l,6-diol, etc.

Examples of saturated dicarboxylic acids (or their anhydrides), ormixtures thereof, which may be reacted with an unsaturated glycol,include oxalic, malonic, succinic, glutaric, adipic, pimelic, suberic,azelaic, sebacic, phthalic, isophthalic, terephthalic,tetrahydrophthalic, hexahydrophthalic, endomethylene tetrahydrophthalic,tetrachlorophthalic, hexachloroendomethylene tetrahydrophthalic,2,2-oxydiacetic, 2,2'- and 3,3'-oxydipropionic, 2,2'-, 3,3- and4,4-oxyclibutyric acids and the like.

Examples of unsaturated dicarboxylic acids (or their anhydrides), ormixtures thereof, which may be reacted with a saturated or unsaturatedglycol include any of the dibasic acids mentioned in the precedingparagraph and/ or maleic, fumaric, chloromaleic, citraconic, itaconic,mesaconic acids and the like.

Some specific polyesters include, for example, the polyester of maleicanhydride with ethylene glycol, fumaric acid with diethylene glycol,itaconic acid with 1,6-hexanediol, adipic acid with 2-butene-l,4-diol,phthalic anhydride with 3-hexene-l,6-diol, maleic anhydride with 2-butene-l,4-diol, and the like.

In accordance with known practice, one or more saturated glycols ordibasic acids may be blended and copolymerized with the essentialmonomeric components referred to above to provide any desiredmodifications in the properties of the resulting polyunsaturated linearpolyesters employed herein.

One of the advantages of the process of the present invention ascompared with prior processes employing a polyolefinic monomer compoundin the foamable plasticized vinyl resin system resides in the fact thatthe present polymerizable system, employing substantial proportions ofthe less expensive monoolefinic monomers, yields substantial economicsavings. Another advantage resides in the relatively higher proportionsof olefinic sites available for cross-linking as compared with thepreviously employed polyolefinic monomers. Still another advantageresides in the fact that such polyolefinic monomers have a relativelygreater tendency to ho'mopolymerize in the foamable vinyl resin blendprior to the blowing step and/r application of the polymerizationcatalyst, thereby pro tanto reducing the capacity to foam throughout thevinyl resin sheet. The present invention involving a completeelimination of use of such monomers enables the attainment of furtherimproved differential embossed effects.

The monomer containing only a single olefinically unsaturated site maybe practically any of the conventional monomer materials well known inthe art. Exemplary groups of such conventional monomers include, forexample, the vinyl aromatic compounds, vinyl esters, acrylic andmethacrylic acids, and derivatives, i.e. esters, thereof. Accordingly,such monomers containing only one olefinically unsaturated groupingwhich can be employed in accordance with the improved process of thepresent invention include, for example, styrene, alkyl and arylsubstituted styrene, e.g. para-ethyl styrene, para-phenyl styrene, etc.;vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate,etc.; and alkyl acrylates and methacrylates such as acrylate, t-butylacrylate, isobutyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate,lauryl acrylate, stearyl acrylate, Z-methoxyethyl acrylate,methyl-a-chloroacrylate, methyl-a-cyanoacrylate, propyl thioacrylate;methyl methacrylate, n-butyl methacrylate, secbutylmethacrylate,isobutyl methacrylate, isodecyl methacrylate, lauryl methacrylate,stearyl methacrylate, 2-hy droxyethyl methacrylate, Z-hydroxypropylmethacrylate, glycidyl methacrylate, etc.

Other suitable monoethylem'cally unsaturated monomers which can beemployed in accordance with the process of the present inventioninclude, for example, such conventional monomers as alkyl vinyl ethers,e.g. methyl and isobutyl vinyl ether, etc.

While a single monoethenically unsaturated monomer can of course beemployed in accordance with the process of the present invention,mixtures of such monoethenically unsaturated monomers can beadvantageously employed where desired. Thus, for example, suitablemixtures can comprise styrene and methyl methacrylate, maleic anhydrideand isobutyl vinyl ether, etc.

In general, the total amount of both types of polymerizable componentsshould be about 1 to 40%, preferably about 5 to 25%, and optimally about20% by weight of the vinyl resin in the foamable layer, and about 0.3 to3, preferably about 1 to 3 parts of the monoolefinic monomer should beemployed per part by weight of the polyunsaturated polyester.

To these essential ingredients, the resin, the plasticizer, the blowingagent, and the polymerizable components, there may be added otheringredients such as pigments, dyes, or other decorative elements inamounts ranging from a small fraction up to about 20% by weight,depending on the results desired. Relatively small amounts of a granularfiller such as a clay, a limestone, or a silicate may be used. However,the composition will not be highly filled in view of a need for at leasta portion of the composition to expand and form a cellular or foamedregion. Fillers to be used, if any, will normally be present in lessthan about 20% by weight of the total composition. Small amounts of heatand light stabilizers as described above will also be incorporated inaddition to the barium-cadmium salts of long-chain fatty acids, polyolssuch as pentaerythritol and ot-methylglucoside, nitrogen compounds suchas melamine and dicyandiamide, esters such as triethylene glycolsalicylate, and mixtures thereof.

The above-defined components are blended and formed into a sheet by anyconventional method known in the art. Thus, for example, the plastisolcomposition may be doctored, roll coated, or otherwise applied to astrippable carrier sheet or to a permanent backing which may be solidplastic such as vinyl or polyolefin film, or a woven or more generally,felted fibrous sheet such as rubber or plastic-bonded asbestos and/orglass and/or cellulosic felts and the like. The thermoplastic sheetproduced in accordance with the process of the present invention willgenerally have a thickness within the range of about 0.01 to about 0.2inches exclusive of any backing material. This thermoplastic sheet isgelled to facilitate printing thereon, and to the gelled sheet isapplied a printing ink in a predetermined pattern, the printing inkcontaining a catalyst effecting the polymerization of the polymerizablesystem at the temperature at which the blowing or foaming agentincorporated in the thermoplastic sheet is decomposed. Accordingly,subsequent application of heat to decompose the blowing agent will alsoeffect the polymerization of the system in those portions of thethermoplastic sheet to which the printing ink containing the catalystshas been applied. Optionally, the printing ink containing the catalysteffective to polymerize the system will contain a liquid that willpenetrate the thermoplastic sheet. This, of course, allows bettercontact of the catalyst and the polymerizable materials.

The catalyst employed in accordance with the process of the presentinvention can be any of the known free radical catalysts conventionallyused to enhance the polymerization of both mono-olefinically andpolyolefinically unsaturated material. They comprise primarily theorganic per-compounds. Among the peroxides that are usable aredi-t-butyl peroxide, benzoyl peroxide, lauroyl peroxide, capryloylperoxide, acetyl peroxide, p-chlorobenzoyl peroxide, cumenehydroperoxide, and the other known peroxide initiators. Large numbers ofsuch peroxides exist, and generally they are broken down into broadergroups comprising low-temperature types, intermediate-temperature types,and high-temperature types. The high-temperature types are thosegenerally used above 212 F. Other per-compounds such as t-butylperbenzoate, and isopropylpercarbonate are usable in the presentprocess. Besides the per-compound type of free-radical initiators, theremay be used such aliphatic azocatalysts as alpha,alpha'-azodiisobutyronitrile.

As indicated previously, the ink composition which is applied in apattern over selected areas of the thermoplastic sheet preferablycontains a liquid capable of penetrating the thermoplastic sheet so asto carry the polymerization catalyst into the thermoplastic sheet tomore effectively promote the polymerization of the system. Such apenetrating liquid generally comprises a carrier liquid, which ispreferably a diluent, solvent, or plasticizer for the particular vinylresin of the thermoplastic sheet. Thus, for example, a mixture ofmethylethyl ketone and dioxane serves as a particularly suitable carrierfor many of the polymerization catalysts. The carrier liquid orpenetrating liquid that is chosen should be one which the polymerizationcatalyst is soluble in or at least partly soluble, so that uponpenetration of the liquid into the thermoplastic sheet the catalyst willbe carried into the sheet for best contact of the catalyst with thepolymerizable material. Where the catalyst is soluble in plasticizerssuch as tributoxyethyl phosphate, then such plasticizers may serve ascarriers for the catalyst.

As indicated previously, the chemical embossed eflfect is obtained bydistributing the catalyst, preferably in the penetrating liquid, overpre-determined areas of the thermoplastic sheet, so that by subsequentapplication of heat the preferential polymerization of the system inthose areas over which the catalyst composition or printing ink has beenapplied will produce areas which are foamed to a lesser extent thanthose areas over which the catalyst composition was not applied.

Application of the carrier liquid containing the catalyst may be carriedout in any convenient manner. The liquid may in fact be used as aprinting ink and may also contain dyes, pigments, filler, wetting agent,stabilizer, and other compounds normally found in ink. Such a coloredink, when printed on an above-described thermoplastic sheet by any ofthe known printing methods, will produce a colored design or patternprinted on the sheet. Subsequent application of heat as describedearlier will then produce foaming in only those areas which have notbeen contacted with this ink.

As indicated previously, as an alternative to applying a catalyst andoptional penetrating liquid directly to the top surface of thethermoplastic sheet, the composition containing the catalyst andoptional penetrating liquid may be applied to a supporting sheet withthe blend of thermo plastic polymer being applied to the supportingsheet above the catalyst composition. Subsequent application of heatsufficient to fuse the blend, decompose the blowing agent, andpolymerize the system will also produce the chemical embossed effect inthis manner.

When the catalyst composition and optional penetrating liquid areapplied to the thermoplastic sheet or supporting sheet the thickness ofthe application will generally range from about 0.1 mils to about 20mils depending somewhat on the ability of the carrier liquid topenetrate the thermoplastic sheet and on the concentration of thecatalyst in the liquid carrier. Depending on the activity of theparticular catalyst selected, the concentration of the catalyst in theink will generally comprise about 3 to about 25% by weight of the totalweight of the ink composition.

age or other interim handling, be dried without causing foaming by theapplication of a gentle heat.

A clear or colored coating of a thermoplastic resin may be then sprayed,doctored, or roll applied over the entire sheet in known manner. Thisfinal coating may contain a flatting agent to control gloss. Suchcoating may consist of a plastisol or organosol, will have littlepigment or filler therein, and may otherwise resemble the foamable layerwithout blowing agent and olefinic material. This clear coat will be thefinal coat and will overlay any printing which has previously beenapplied to the thermoplastic sheet. 0n the application of heat to causefusion of the resin, decomposition of the blowing agent, andpolymerization of the system, the clear coat will also fuse and becomean integral part of the system covering both the raised foam areas andthe low unfoamed areas on the sheet. A protective wear layer is therebyprovided which is especially desirable for floor coverings and the like.

It will of course be understood that the above-described wear layer mayalternatively be provided by laminating in known manner a clear,prefused vinyl sheet to the catalyst-containing pattern layer prior orsubsequent to the above-described blowing and polymerizing heattreatment.

It will also be understood that in accordance with the presentinvention, the formed sheet carrying the catalystcontaining layer, andwear layer if desired, may often with advantage be heated at atemperature below the decomposition temperature of the blowing agent fora period of time to initiate and complete the cross-linking andpolymerization reaction prior to the blowing step, provided suitablepolymerizable materials are employed which polymerize under suchconditions. Such alternative treatment, however, is generally notnecessary when the catalyst is applied to the backing support before thefoamable blend is applied, the heat treatment given during thepreliminary fusing of the foamable blend generally being suflicient.

The improved process of the present invention will now be described byreference to the following specific examples which are onlyillustrative. All parts and proportions referred to herein and in theappended claims are by weight unless otherwise indicated.

together with the following amounts of polymer and monomer:

Blend. A B

Polyester I 5. 0 2. 5 Z-ethylhexyl acrylate 5.0 7. 5

Polyester I is prepared as follows:

Into a flask fitted with a stirrer a thermometer, a gas inlet tubeextending to the bottom of the flask, and a condenser set fordistillation is placed 126.5 g. of ethylene glycol and 186 g. of maleicanhydride. With a fairly rapid stream of nitrogen passing through thegas inlet tube the flask and its contents are heated slowly by an oilbath to about C., the agitation started, and then heating continueduntil the temperature reaches -200 C. The mixture is held at thistemperature until the acid value decreases to 26 mg. KOH/ g. The productis then poured hot into a can and cooled. For use the polyester is firstdissolved in the requisite amount of Z-ethylhexyl acrylate or othermonomer used.

'11 Printing compositions or inks containing an addition polymerizationcatalyst are prepared from the following pigment/binder blend:

' Parts Pigment (2.5 parts Heliogen Blue A in 1 part epoxidized soyaoil) 85 Calcium carbonate 25 'Poly(vinyl chloride-co-vinyl acetate)binder resins 125 Dioctyl phthalate 8 Dispersing agent (polyethyleneglycol monolaurate) 2.4 Aromatic hydrocarbon (toluene) 133 Ketonesolvents (methyl ethyl ketone and methyl isobutyl ketone, 1:1) 477 Theabove pigment/ binder blend is mixed with one of the following peroxidesin the parts given:

Parts Pigment] Peroxide binder (i) Dicumyl peroxide (ii)2,5-dimethyl-2,5-di (t-butylperoxy) exane.

(iii) n-Butyl-4,4-bis (t-butylperoxy)- valerate.

(iv) Dgtgalptyl diperphthalate (50% (v) t-Butyl poracetate (75% inbenzene)...

(vi)..-- t-Butyl peroxyisobutyrate (vii) t-Butyl perbenzoate (viii)Methgl eIEhyl ketone peroxides (50% in (ix)... t-Butyl perocotate xBenzoyl peroxide (xi) Lauroyl peroxide EXAMPLE 2 The procedure ofExample 1 is repeated and similar results obtained using instead ofPolyester I, Polyester II in the preparation of which the procedure forPolyester I is repeated, except that one half of the ethylene glycol isreplaced by 99 g. of 1,4-butanediol. Some tetrahydrofurane (about g.) isrecovered along with the Water from the condensation. The acid value ofthe cooled prodnet is 15 mg. KOH/ g.

EXAMPLE 3 The procedure of Example 1 is repeated and similar resultsobtained using instead of Polyester 1, Polyester HI in the preparationof which the procedure for Polyester I is repeated, except that all ofthe ethylene glycol is replaced by 198 g. of 1,4-butanediol. The cooledproduct has an acid value of 11 mg. KOH/ g.

EXAMPLE 4 The procedure of Example 1 is repeated and similar resultsobtained using instead of Polyester I, Polyester IV in the preparationof which the procedure used for Polyester 1 is employed using 186 g. ofmaleic anhydride and 155 g. of 1,2-propylene glycol. The product has anacid value of 19 mg. KOH/ g.

12 EXAMPLE 5 The procedure of Example 1 is repeated and similar resultsobtained using instead of Polyester I, Polyester V in the preparation ofwhich the procedure for Polyester IV is repeated, except that one halfof the maleic anhydride is replaced by 148 g. of phthalic anhydride, and20 g. of xylene is added to the reaction mixture. A short air condenseris placed between the flask and the take-ofi condenser to provide somereflux to keep the phthalic anhydride within the reaction mixture.Practically all of the xylene is removed finally as water azeotrope. Theacid value of the cooled product is 5 mg. KOH/g.

EXAMPLE 6 The procedure of Example 1 is repeated and similar resultsobtained using instead of Polyester I, Polyester VI in the. preparationof which the procedure for Polyester V is repeated, except that half ofthe 1,2-propylene glycol is replaced by 120.5 g. of 1,6-hexamethyleneglycol. The product has an acid value of 7 mg. KOH/ g.

EXAMPLE 7 The procedure of Example 1 is repeated and similar resultsobtained using instead of Polyester I, Polyester VII in the preparationof which the procedure for Polyester I is repeated, except that half ofthe ethylene glycol is replaced by 107 g. of diethylene glycol. The acidvalue of the cooled product is .0 mg. KOH/g.

This invention has been disclosed with respect to certain preferredembodiments, and it will be understood that modifications and variationsthereof will become obvious to persons skilled in the art and areintended to be included within the spirit and purview of thisapplication and the scope of the appended claims.

We claim:

1. A process for providing an embossed appearance to a thermoplasticsheet which comprises forming into a sheet a blend devoid ofpolymerization catalyst and consisting essentially of:

(1) a thermoplastic vinyl resin;

(2) a plasticizer for said vinyl resin in an amount of from 20 topercent by weight based on the weight of the resin;

(3) a blowing agent which decomposes when heated at a temperature withinthe range of above the glass transition temperature of the plasticizedresin and below the decomposition temperature of said resin, saidblowing agent being uniformly distributed throughout the blend and beingpresent in an amount of from 0.5% to 15% by weight based on the weightof the resin;

(4) a polyolefinically unsaturated linear polyester capable ofcopolymerization or further polymerization in said temperature range inthe presence of an addition polymerization catalyst; and

(5) about 0.3 to 3 parts, per part by weight of polyester (4), of atleast one monomer containing only one olefinically unsaturated site andpolymerizable in said temperature range in the presence of an additionpolymerization catalyst.

applying to portions of said sheet, in a predetermined pattern, anaddition polymerization catalyst composition which will causepolymerization of olyester (4) and monomer (5) in said temperaturerange, and subsequently heating the resultant sheet within saidtemperature range to fuse the plasticized resin, decompose the blowingagent and polymerize said polyester and monomer which are employed insaid blend in a total amount of from about 1 to 40% by weight of saidresin.

2. The process of claim 1 wherein said vinyl resin is polyvinylchloride.

3. The process of claim 1 wherein said catalyst is a peroxide catalyst.

4. The process of claim 1 wherein said catalyst composition contains aliquid capable of penetrating said thermoplastic sheet.

5. The process of claim 4 wherein said liquid capable of penetratingsaid thermoplastic sheet is a plasticizer therefor.

6. The process of claim 4 wherein said liquid capable of penetratingsaid thermoplastic sheet is a solvent therefor.

7. The process of claim 1 wherein said catalyst composition contains acoloring material.

8. The process of claim 1 wherein said vinyl resin is polyvinylchloride,a copolymer of vinyl chloride with a member of the group consisting ofvinyl esters, lower alkyl vinyl ethers, acrylic acid, methacrylic acid,and lower alkyl esters of such acids, or a mixture of polyvinylchloridewith at least one polymer derived from said members.

9. The process of claim 1 wherein said polyester (4) is a polymer of anester derived by reaction of maleic anhydride with an alkylene glycol orpolyalkylene glycol.

10. The process of claim 1 wherein said monomer (5) is selected from thegroup consisting of styrenes, vinyl esters, alkyl vinyl ethers, alkylacrylates, and alkyl methacrylates.

References Cited UNITED STATES PATENTS Fourcade et a1. 260-2.5 N

Isaacs et al. 260-31.6

Szalay 26031.6 Witman 161116 Roberts 26445 Crowley l61-159 Rugg 26452Birkett et al. 26452 Fry 2603l.6 Slosberg et al. 161-5 Marriott et a1.156--232 'Grubb 264-54 Hosoda et al. 26454 DONALD E. CZAJA, PrimaryExaminer R. W. GRIFFIN, Assistant Examiner U .8. Cl. X.R.

161-DIG. 3; 260- P, 2.5 N; 26445, 54

